Machine tool having rotary and indexible work table

ABSTRACT

A machine took, primarily for producing slots in a workpiece, has a rotatable work-table for supporting the workpiece, a cutter head on which a rotatable cutting tool is carried and a support frame for the cutter head. The cutter head is movable relative to the support frame and work-table drive means rotates the worktable in a series of accurately predetermined increments or continuously. The increments of movement of the work-table are variable in magnitude and the cutting tool makes a cut in the work-table between each incremental movement. Two cutter heads are normally provided both of which are carried on a common support frame.

United States Patent Lancaster et al.

[ 3,680,439 51 Aug. 1,1972

MACHINE TOOL HAVING ROTARY AND INDEXIBLE WORK TABLE 2,890,590 6/1959 Oi-iarah ..74/820 X 2,539,506 1/1951 Bura ..90/56 X Primary Examiner-Gil Weidenfeld Attorney-Mawhinney & Mawhinney ABSTRACT A machine took, primarily for producing slots in a workpiece, has a rotatable work-table for supporting the workpiece, a cutter head on which a rotatable cutting tool is carried and a support frame for the cutter head. The cutter head is movable relative to the [30] Foreign Application Priority Data f d In bl d t h support rame an wor a e rive means rota es e g g t 3'53! work-table in a series of accurately predetermined intea n m crements or continuously. The increments of move- [52] us Cl gulls] 90/56 A 74/820 ment of the work-table are variable in magnitude and 511 Int. Cl. ..B23e1/14, B23' 17/18 cutting tool makes a cut in the work-table between [58] Field of Search ..90/l5.l,56, 56A; 408/71; each incremental movement. Two cutter heads are I 74 320 1 51/2155 normally provided both of which are carried on a [56] References Cited UNITED STATES PATENTS 17 Claims, 20 Drawing Figures 3'054333 95? BW'E Qdist-'37: 721

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PATENYEmus 1 m2 sum 01 0F 16 FIG].

INVENTORS JAMES KENNETH LANCASTER DAvu WILLIAM YATES PATENTEDAUG 1 I 2 SHEET 02 or 1B PATENTEmus 11912 3.680.439

sum on HF 16 INVENTORS mes beurqsru LANCASTER vu WILLIAM YATES PATENTEDAUB 1 I972 SHEET 08 0F 16 IN E VENTORS H LANCABTEQ ATES.

JAMES DAVID PATENTEDAus" 1 1972 SHEET 09 HF 16 INVENTORS JAMES KENNETH LANCAQTEE DAV: W\L L IA YATES,

PATENTEDAUE 1 1972 sum 11 [1F 16 3G0 FIGIS. 298

INVENTORS JAmEs KENNETH LAN ASTEEI DAvlb WILUAM YATES,

PATENTEDAUB 11972 3.680.439

saw 12 nr 16 VENTOR AME-'5 NNET ANC 5752,

WILLINW AYES,

PATENTEDAUG H972 3.680.439

SHEET 130F16 INVENTORS JAMES KENNE. H LANCAQERI DAvnb W I L L I A m A T ES.

PATENTEDAUB 1 I972 SHEET lu 0F 16 fi I HH IWV U 6.

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INVENTORS s. K NNETH LA-cAswsz Wn.

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PATENTEDAUB 1 I972 SHEET 1SUF1'6 INVENTORS JAMES KENNETH LANCASTER b v| WlLLlAM YATES PATENTEDAUB H912 3.680.439

SHEET 15 [1F 16 FIG.20.

INVENT S Ame's KENNCTH ANCASTBR we. WILLIAMY\TES MACHINE TOOL HAVING ROTARY AND INDEXIBLE WORK TABLE This invention relates to machine tools and particularly, but not exclusively, to tools which are arranged to cut grooves, slots or the like at predetermined spacings in the surface of a workpiece.

Machine tools are required which have a work table on which the workpiece is mounted and in which the table is rotatable in predetermined increments, and in which after each increment of rotation a cutter cuts a slot in the workpiece. In many applications it is important that the slots be very accurately spaced around the workpiece and that the spacing of the slots be formed at variable spacings. The means for rotating the table should be sufficiently accurate to always rotate the table in equal increments, especially when the increments are small, and an unacceptable cumulative error in the spacings may occur which renders the finished workpiece unacceptable. The desirability of providing means whereby the table may be rotated continuously to center the workpiece, and the desirability of providing means for interrupting the cutting sequence, for example in the event of a broken cutter tool, make for further complications in providing suitable means for rotating the work table.

Furthermore some workpieces may require two sets of slots formed in them at predetermined interrelated positions, and hitherto each set of slots has had to be produced in a separate cutting operation. In order to save time it is desirable that one cutting machine should be capable of cutting both sets of slots simultaneously.

An object of the invention is to provide a machine tool which meets at least some of the above characteristics and which incorporates an indexing mechanism capable of accurately indexing the workpiece after each machining operation.

According to one aspect of the invention a machine tool comprises a rotatable work table for supporting a workpiece, a cutter head on which a rotatable cutting tool for acting on the workpiece is arranged to be carried, a support frame for the cutter head, drive means for rotating the cutting tool, drive means for moving the cutter head relative to the associated cutter head support frame, and drive means for driving the work table in a series of accurately predetermined incremental movements and for continuously rotating the work table, the increments of movement of the work table being variable in magnitude.

Preferably the drive means for the cutter head is arranged to move the cutter head radially of or parallel to the axis of rotation of the work table.

The machine may comprise two cutter heads each having drive means for moving the cutter heads relative to their associated support frame, one cutter head being movable radially of the work table and the other being movable parallel to the axis of rotation of the work table.

The cutter heads may be mounted on a common support frame.

According to a further feature of the invention the machine tool comprises two or more cutting heads mounted on a common support frame for movement with respect to the support frame.

Each of the cutter heads may have a guide co-operating with a guideway on the support frame, and the drive means, which is arranged to move each guide along the associated guideway, may include a rotatable screwthreaded shaft which is in screw-threaded engagement with the cutter head.

The drive means for moving the or each cutter head relative to the associated support frame may be operable at at least two speeds, one speed being for movement of the cutter head during a cutting operation of the cutting tool and the other, relatively faster speed being for returning the cutting head to its initial position with respect to the support frame.

According to a further feature of the invention the support frame includes a cutter body upon which the cutter head is supported, the cutter head being movable by said drive means relative to the cutter body and the cutter body being movable relative to the support frame in a direction at a right angle with respect to said movement of the cutter head relative to the cutter body.

The drive means for moving the or each cutter head relative to the cutter body may be carried on the cutter body.

Conveniently the drive means for the cutting tool includes change speed means for varying the rotational speed of the cutting tool and the drive means for the cutting tool is carried on the cutter head.

According to a still further feature of the invention the drive means for the work table includes a drive m0- tor, a geneva mechanism, and a worm and worm wheel, the geneva mechanism being selectively engageable with the drive motor and the worm and worm wheel to obtain variable increments of movement of the work table.

The work table drive means may include clutch means whereby the work table is drivable in increments through the geneva mechanism or is drivable continuously by-passing the geneva mechanism.

Conveniently the drive to the work table from the drive motor is disconnectable and the work table is rotatable manually independently of the drive motor and geneva mechanism.

According to a further aspect of the invention a machine tool comprises a work table for supporting a workpiece, two cutting heads on each of which a rotatable cutting tool for acting on the workpiece is arranged to be carried, a support frame common to both cutter heads on which the cutter heads are supported, drive means carried on each cutter head for rotating the associated cutting tool, and drive means for moving the cutter heads relative to the support frame.

Preferably the machine tool comprises drive means for rotating the work table in a series of accurately predetermined incremental movements and for continuously rotating the work table, the increments of movement of the work table being variable in magnitude.

Further features of the invention appear from the following description of an embodiment of the invention given by way of example onlyand with reference to the drawings, in which:

FIG. 1 is a plan view of a complete machine,

FIG. 2 is a side elevation in the direction of arrow 2 in FIG. 1,

FIG. 3 is a side elevation in the direction of arrow 3 in FIG. 1,

FIG. 4 is a section through the machine base and work table,

FIG. 5 is a plan view of the machine work table,

FIG. 6 is a sectional plan view of the work table drive means,

FIG. 7 is a sectional view through the worm shaft of FIG. '6,

FIG. 8 is a sectional end elevation of the drive means of FIG. 6,

FIG. 9 is a part section on the line 9-9 in FIG. 8,

FIG. 10 is a part section on the line 1010 in FIG. 9,

FIG. 11 is an end elevation in the direction of arrow 1 1 in FIG. 12,

FIG. 12 is a sectional elevation on the line 12-12 in FIG. 10,

FIG. 13 is a side elevation of the machine turret,

FIG. 14 is a cross section on the line 14-14 in FIG. 15,

FIG. 15 is a front elevation of a cutter head,

FIG. 16 is a cross section of the drive transmission to the cutter head.

FIG. 17 is a cross section of the transmission of FIG. 16 in a plane at a right angle to the plane of FIG. 16,

FIG. 18 is a side elevation partly cut away of the transmission of FIGS. 16 and 17,

FIG. 19 is a cross section of part of the transmission of FIGS. 16-18, and

FIG. 20 is a section of part of the transmission of FIGS. 16-19.

Referring firstly to FIGS. 1 to 3 a machine is shown which has a fabricated base 20 on which is mounted a rotary spindle 21, and a face plate or work table 22 is removably attached to the spindle 21. The face plate 22 is replaceable to allow for difierent sizes of workpieces 23 to be secured to the face plate. The face plate 22 is rotatable with the spindle by drive means (see FIGS. 4-12) located within the base 20 below the face plate 22.

A control console 190 which houses an electrical control system for the machine is located at one side of the base 20 and the base also includes a tank 191 for lubricant for the machine.

Horizontal and vertical cutter assemblies 192 and 193 respectively are mounted on a common vertical turret or support frame 194 which is rigidly secured to the base 20 so that the whole of the basic structure of the machine is rigid and able to withstand cutting forces without significant distortion.

The horizontal and vertical cutter assemblies are very similar to one another in construction except that the horizontal cutter assembly 192 is turned through 90 with respect to the vertical cutter assembly 193. One only of the cutter assemblies will be described later in detail and, except where stated to the contrary, the two cutter assemblies are identical.

Each cutter assembly has two electric motors 195 and 196, and one motor 195 is for driving a cutter wheel 197 which is carried by a cutter spindle 198. The other motor 196 is for feeding the cutter wheel 197 in a reciprocal movement as it acts on the workpiece.

The cutter assemblies 192 and 193 include cutter heads 199 and 200 respectively on which the motors 195 are mounted and which contain transmission gearing in driving engagement with the respective motors 195. The horizontal cutter head 199 is movable horizontally along slides 201 and the vertical cutter head 200 is movable vertically along further slides 202.

The horizontal cutter head 199 is carried on a vertically movable cutter body 203 which is movable with respect to the turret 194 along slides 204. The vertical cutter head 200 is carried on a similar cutter body 205 which is movable horizontally along slides 206.

The vertical cutter head 200 effects a cutting action during downward movement of the head and, after a slot of the required length has been formed in the workpiece, the head is returned to its initial position above the workpiece. The return movement of the cutter head 200 is quicker than the cutting movement in order to save operating time. Thus for one cutting operation the cutter head 200 has extreme lower and upper positions and automatic control of the motion of the cutter head vertically is obtained by switches 39 mounted on the cutter body 205. The switches 39 each have a lever contactable by a cam 40 carried on the cutter head. When the cutter head 200 is in its lowermost position the cam 40 contacts a lever and the lower switch 39 is operated to cause the cutter head to stop downward movement of the head and initiate upward movement of the head. When the head 200 reaches the uppermost position the cam 40 contacts the lever on the upper switch 39 and stops upward movement of the head. During the upward non-cutting movements the cutter wheel 197 continues to rotate and passes along the slot already formed in the workpiece. The vertical positions of the switches 39 may be varied to vary the stroke of the head.

The horizontal cutter head 199 has similar switches 39 and a cam 40 for controlling the movement of the head relative to the cutter body 203 during cutting action of its cutter wheel 197.

The cutter heads and drive means are more fully described with reference to FIGS. 13-20.

Referring now to FIG. 4 the base 20 supports a tubular member 207 on ribs 208 upstanding from a base plate 209. The member 207 carries a bearing 210 for the lower end of the spindle 21.

The spindle 21 has a sleeve 211 with a radially extending disc 212 having an integral annulus 213 on which a worm wheel 214 having teeth 215 is secured. The sleeve 211 is keyed to the spindle 21 by a key 216 and the spindle is driven through the worm wheel 214 and a driven worm (FIG. 5). Towards its upper end the spindle 21 passes through a sleeve 218 which is secured to a cover 219 and the cover is secured to a top plate 220 of the base 20. The spindle 21 is formed at its upper end with a disc 221 to which the face plate 22 is secured.

A drive motor 217 (FIG. 2) for the spindle 21 is provided and a drive means and transmission for driving the spindle is of the form which enables the spindle to be rotated in accurately predetermined variable increments and also enables the spindle to be rotated continuously. Provision is made for the spindle to be uncoupled from the drive motor and rotated continuously by hand. The drive means and transmission for the spindle 21 are described with reference to FIGS. 5-12.

In the present construction the drive to the spindle is located in the base, and the spindle 21 and associated worm wheel 214 are readily removable from its support.

In FIG. 4 can be seen the tank 191 and a pump 224 for circulating lubricating oil to the machine.

Reference is now made to FIG. 5 in which a tapered worm shaft 62 is located in a portion 52 of the base and has a helically-arranged toothed portion which engages the teeth 215 on the wheel 214. The worm shaft 62 is carried in bearing blocks 65 secured to the base portion 52 by bolts 66. The bearing blocks 65 locate needle bearings 67 and a taper bearing in which the shaft 62 rotates and one end of the shaft 62 extends beyond the side of the housing 52 and is formed of square-section as at 68 for engagement by a spanner (not shown) by which the worm shaft can be adjusted axially to eliminate backlash.

The opposite end of the shaft 62 makes a splined connection 69 with a coaxial shaft 70 and the shaft 70 extends to adjacent the periphery of the housing 52 and is splined at 71 to receive a similarly splined input shaft 132 (see FIG. 6).

We refer now particularly to FIGS. 6-12 which show drive means including an indexing mechanism for driving the worm shaft 62 (FIG. 4) in predetermined increments and means for driving the shaft 62 in a continuous rotational movement. The electric motor 217 provides the drive for both these movements and has an output shaft 76 which is keyed to a shaft 77 carrying a gear wheel 78.

The shaft 77 extends beyond the gear wheel 78 to an electrically-operated clutch 79 which includes a member 80 rotatable with the shaft 77 and housing the coils of an electro-magnet. The clutch 79 also includes a driven member 81 adjacent the member 80'and at tracted towards and into driving engagement with the member 80 when the electro-magnet is operative. Thus when the clutch 79 is engaged a shaft 82 drivingly secured to the driven member 81 is rotated. v

The shaft 82 carries helical worm teeth (not shown) arranged to engage a worm wheel 84 keyed to a shaft 85 (shown more clearly in FIG. 7). The shaft 82 extends beyond the teeth and has at its end remote from the motor 75 an electrically-operated brake assembly 86.

The shaft 85 carries a disc plate 87 keyed to and coaxial with the shaft 85 and a roller pin 88 (see FIG. 8) is attached to the disc 87. The shaft 85 also carries a cam plate 89 keyed to the shaft and the shaft 85 is located in end bearings 90 and 91. The disc 87 and the cam plate 89 each form part of a geneva mechanism shown more clearly in FIG. 8.

The geneva mechanism also includes a disc 92 having four equally-spaced radial slots 93 arranged to receive the pin 88, and the disc 92 is rotated by the pin 88 on rotation of the disc plate 87 and engagement of the pin 88 in one of the slots 93. A further disc 94 is coaxial with the disc 92 and is mounted for rotation with the disc 92 about a common shaft 95. The disc 94 is axially spaced from the disc 92 and is of smaller' diameter than the disc 92 and has four radial slots arranged intermediate the slots 93 in the disc 92 and for receiving a projection 96 on a locking plate 97.

The locking plate 97 is mounted for reciprocal sliding movement in guides 98 and carries a wear plate 83 at the opposite end to the projection 96, and a roller 99 secured to the plate 97 so as to project beyond the plate 97 into the space 100 in the plate 97 in which the cam plate 89 is located. The cam plate 89 has a cam periphery 101 which engages the roller 99 and a springloaded rod 102 engages the wear plate 83 and urges the locking plate 97 towards the disc 94 in opposition to the action of the cam 89 on the roller 99.

The disc 87 carries a trip 103 which rotates with the disc 87 and contacts a spring-loaded plunger 104 of a switch device 105, depression of the plunger 104 by the trip device causing a signal to be transmitted to the electrical control system (not shown) of the machine to disengage the clutch 79 and apply the brake 86.

The shaft 95 is driven in increments by the geneva mechanism and extends through the housing to be coupled to a shaft 106 by a clamping arrangement (FIG. 6) including an annular disc 107 and a bracket 108 held together by bolts 109 and clamping a disc-like enlargement at the end of the shaft 106. On release of the bolt 109 the clamping arrangement is released and the shafts 95 and 106 are rotatable independently. The face plate 22 can be rotated by hand with the bolt 109 released by revolving a gear wheel 116.

The indexing drive to the work table is transmitted from the shaft 106 through gearing shown more clearly in FIGS. 11 and 12. The gearing includes a gear wheel 110 mounted for rotation with the shaft 106 and secured to the shaft 106 by a nut 111. The gear wheel 110 engages a gear wheel 112 carried on an intermediate gear shaft 113 carried on a support bracket 114. A further gear wheel 115 is also carried on the shaft 113 for rotation with the wheel 112, and the gear wheel 115 engages with a final gear wheel 116 in the gear train. The gear wheel 116 is secured for rotation with'a drive shaft 117 which extends through the housing for driving engagement with the shaft 70 (FIG. 5).

The bracket 114 is arranged to accommodate any combination of gear wheels 110, 112, 115 and 116 so that the gear ratio of the gearing from the geneva mechanism may be varied according to magnitude of the desired indexing movement of the work table. Thus the bracket 114 is formed with a disc-like portion 118 having two opposed part-annular slots 119 in each of which are located a nut and bolt 120. The bracket 114 also has an integral arm portion 121 with a longitudinal slot 122 through which the shaft 113 is located and secured by a nut 123. The bracket 114 may be rotated about the shaft 117 on release of the nuts 120, and the intermediate shaft 113 may be located in any position along the slot 122 so as to assume any desired position in relation to the shafts 106 and 117 in accordance with the arrangement of gearing. The gear wheels may be readily replaced by release of the securing nuts 120, 111 and 123.

During certain phases of the operation of the machine it is required to rotate the work table continuously, for example, when centering the work piece on the table. Drive for continuous rotation is also taken through the gear wheel 78 (FIG. 6) from the motor 217. An intermediate gear wheel (not shown) engages the gear wheel 78 and also a gear wheel 124 carried on a shaft 125 so that the drive is transmitted from the motor to the shaft 125 as long as the motor 217 is rotating. The shaft 125 is located in bearings 126 and extends through the housing to drivingly engage a gear 

1. A machine tool comprising a rotatable worktable for supporting a workpiece, a cutter head on which a rotatable cutting tool for acting on the workpiece is arranged to be carried, a support frame for the cutter head, drive means for rotating the cutting tool, drive means for moving the cutter head relative to the associated cutter head support frame, and selective drive means for driving the worktable in a series of accurately predetermined incremental movements or for continuously rotating the worktable, and for providing said incremental movements of the worktable to be variable in magnitude.
 2. A machine tool according to claim 1 wherein the drive means for the cutter head is arranged to move the cutter head radially of or parallel to the axis of rotation of the worktable.
 3. A machine tool according to claim 2 wherein two cutter heads are provided each having drive means for moving the cutter heads relative to their associated support frame, one cutter head being movable radially of the worktable and the other being movable parallel to the axis of rotation of the worktable, the two cutter heads being mounted on a common support frame.
 4. A machine tool according to claim 1 comprising two or more cutting heads mounted on a common support frame for movement with respect to the support frame.
 5. A machine tool according to claim 4 wherein each of the cutter heads has a guide co-operating with a guideway on the support frame, and the drive means, which is arranged to move each guide along the associated guideway, includes a rotatable screw-threaded shaft which is in screw-threaded engagement with the cutter head.
 6. A machine tool according to claim 1 wherein the drive means for moving said cutter head relative to the associated support frame is operable at at least two speeds, one speed being for movement of the cutter head during a cutting operation of the cutting tool and the other, relatively faster speed being for returning the cutting head to its initial position with respect to the support frame.
 7. A machine tool according to claim 1 wherein the support frame includes a cutter body upon which the cutter head is supported, the cutter head being movable by said drive means relative to the cutter body and the cutter body being movable relative to the support frame in a direction at a right angle with respect to said movement of the cutter head relative to the cutter body.
 8. A machine tool according to claim 7 wherein the drive means for moving said cutter head relative to the cutter body is carried on the cutter body and includes change speed means for varying the rotational speed of the cutting tool.
 9. A machine tool according to claim 1 wherein the drive means for the cutting tool is carried on the cutter head.
 10. A machine tool according to claim 1 wherein the the drive means for the worktable includes a drive motor, a geneva mechanism, and a worm and worm wheel, the geneva mechanism being selectively engageable with the drive motor and the worm and worm wheel to obtain variable increments of movement of the worktable.
 11. A machine tool according to claim 10 wherein the worktable drive means includes clutch means whereby the worktable is drivable in increments through the geneva mechanism or is drivable continuously by-passing the geneva mechanism.
 12. A machine tool according to claim 12 wherein the drive to the worktable from the drive motor is disconnectable and the worktable is rotatable manually independently of the drive motor and geneva mechanism.
 13. A machine tool according to claim 12, wherein the worm wheel of the worktable drive means is coaxial with and secured to the worktable and the worm which engages the worm wheel includes means for taking up play between the worm wheel and the worktable drive means is arranGed so that the worktable can only be rotated in one direction.
 14. A machine tool according to Claim 12 wherein the drive means for the worktable includes adjustable gearing whereby the increments of movement of the worktable determined by the geneva mechanism are varied.
 15. A machine tool according to claim 1 wherein the cutter head includes a rotatable spindle on which a cutting wheel is arranged to be drivably supported, the spindle being removable whereby different sizes of cutting wheel can be fitted to the cutter head.
 16. A machine tool according to claim 15 wherein the spindle is axially movable whereby the cutting wheel can be centered after fitting different sizes of cutting wheel to the spindle.
 17. A machine tool comprising a worktable for supporting a workpiece, two cutting heads on each of which a rotatable cutting tool for acting on the workpiece is arranged to be carried, a support frame common to both cutter heads on which the cutter heads are supported, drive means carried on each cutter head for rotating the associated cutting tool, and drive means for moving the cutter heads relative to the support frame, and selective drive means for driving the worktable in a series of accurately predetermined incremental movements or for continuously rotating the worktable, and for providing said incremental movements of the worktable to be variable in magnitude. 